Archive for August, 2008

Kate lentää laskukierroksen Cirrus SR20:llä Palo Altossa

Tämä video on kuvattu lokakuussa 2007 Palo Altossa. Tämä oli Katen ensimmäinen lento Cirrus SR20:llä:
Linkki youtubeen

Huomaa: Youtube-videon laatu ei ole yhtä hyvä kuin Vimeo-videossa.

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Kate lentää laskukierroksen Cirrus SR20:llä Palo Altossa

Tämä video on kuvattu lokakuussa 2007 Palo Altossa. Tämä oli Katen ensimmäinen lento Cirrus SR20:llä:
Linkki youtubeen

Huomaa: Youtube-videon laatu ei ole yhtä hyvä kuin Vimeo-videossa.

NACA 66-020, 66-025, 66-030 body drag coefficient

Some numbers from Javafoil using the Drela approximation method (Xfoil after 1991):


NACA 66-020

Parameters: Length 6 meters, diameter from thickest point 1.2 meters:

α Re Cl Cd Cm 0.25 TU TL SU SL L/D A.C.
[°] [-] [-] [-] [-] [-] [-] [-] [-] [-] [-]
0.0 11.60E6 0.000 0.00709 -0.000 0.623 0.623 1.000 1.000 0.000 0.380

So estimated Cd for the fuselage is 0.00709. Doors, antennas, landing gear door, etc. will make it worse.

Bugs and dirt on the fuselage surface and the results becomes:

NACA 66-020

α Re Cl Cd Cm 0.25 TU TL SU SL L/D A.C.
[°] [-] [-] [-] [-] [-] [-] [-] [-] [-] [-]
0.0 11.60E6 0.000 0.01212 -0.000 0.625 0.625 1.000 1.000 0.000 0.380

NACA 66-030 (engine nacelle variant of the laminar body)

m/S = 1
α Re Cl Cd Cm 0.25 TU TL SU SL L/D A.C.
[°] [-] [-] [-] [-] [-] [-] [-] [-] [-] [-]
0.0 11.60E6 0.000 0.00775 -0.000 0.605 0.603 1.000 1.000 0.000 0.456

Cd = 0.00775

With NACA 66-025 the fuselage pod length drops to 4.8 meters.

NACA 66-025

m/S = 1
α Re Cl Cd Cm 0.25 TU TL SU SL L/D A.C.
[°] [-] [-] [-] [-] [-] [-] [-] [-] [-] [-]
0.0 9.28E6 0.000 0.00812 -0.000 0.612 0.612 1.000 1.000 0.000 0.417

Cd = 0.00818

Conclusion: All of these pods provide (according to simulation), a low drag coefficient.

Equivalent drag area for NACA 66-025 assuming body diameter of 1.2 meters:

0.00818*(0.6m*0.6m*3.14159) = 0.00925 m^2 (=0.0823 sq ft)

Hmm. did I calculate correctly? Somehow looks quite small.

NACA 66-020, 66-025, 66-030 body drag coefficient

Some numbers from Javafoil using the Drela approximation method (Xfoil after 1991):


NACA 66-020

Parameters: Length 6 meters, diameter from thickest point 1.2 meters:

α Re Cl Cd Cm 0.25 TU TL SU SL L/D A.C.
[°] [-] [-] [-] [-] [-] [-] [-] [-] [-] [-]
0.0 11.60E6 0.000 0.00709 -0.000 0.623 0.623 1.000 1.000 0.000 0.380

So estimated Cd for the fuselage is 0.00709. Doors, antennas, landing gear door, etc. will make it worse.

Bugs and dirt on the fuselage surface and the results becomes:

NACA 66-020

α Re Cl Cd Cm 0.25 TU TL SU SL L/D A.C.
[°] [-] [-] [-] [-] [-] [-] [-] [-] [-] [-]
0.0 11.60E6 0.000 0.01212 -0.000 0.625 0.625 1.000 1.000 0.000 0.380

NACA 66-030 (engine nacelle variant of the laminar body)

m/S = 1
α Re Cl Cd Cm 0.25 TU TL SU SL L/D A.C.
[°] [-] [-] [-] [-] [-] [-] [-] [-] [-] [-]
0.0 11.60E6 0.000 0.00775 -0.000 0.605 0.603 1.000 1.000 0.000 0.456

Cd = 0.00775

With NACA 66-025 the fuselage pod length drops to 4.8 meters.

NACA 66-025

m/S = 1
α Re Cl Cd Cm 0.25 TU TL SU SL L/D A.C.
[°] [-] [-] [-] [-] [-] [-] [-] [-] [-] [-]
0.0 9.28E6 0.000 0.00812 -0.000 0.612 0.612 1.000 1.000 0.000 0.417

Cd = 0.00818

Conclusion: All of these pods provide (according to simulation), a low drag coefficient.

Equivalent drag area for NACA 66-025 assuming body diameter of 1.2 meters:

0.00818*(0.6m*0.6m*3.14159) = 0.00925 m^2 (=0.0823 sq ft)

Hmm. did I calculate correctly? Somehow looks quite small.

Hello

This blog contains all my blogs in one.

Why I created this blog? Because I got treated badly in the Blogger service. My aircraft review blog was considered to be contain spam and obviously it was a false positive. I requested review to the blog, but no review has been so far done and my aircraft review blog remains locked. I am really unhappy to the very bad service of Google and hereby created this new blog, which also works as a backup to my postings, so Google don’t get them destroyed.

This is the message I got from the Blogger:

   Hello,

   Your blog at: http://lentokone.blogspot.com/ has been identified as a potential spam blog.  To correct this, please request a review by filling out the form at ….

   Your blog will be deleted within 20 days if it isn’t reviewed, and you’ll be unable to publish posts during this time. After we receive your request, we’ll review your blog and unlock it within two business days. If this blog doesn’t belong to you, you don’t have to do anything, and any other blogs you may have won’t be affected.

   We find spam by using an automated classifier. Automatic spam detection is inherently fuzzy, and occasionally a blog like yours is flagged incorrectly. We sincerely apologize for this error. By using this kind of system, however, we can dedicate more storage, bandwidth, and engineering resources to bloggers like you instead of to spammers. For more information, please see Blogger Help: http://help.blogger.com/bin/answer.py?answer=42577

   Thank you for your understanding and for your help with our spam-fighting efforts.

   Sincerely,

   The Blogger Team

Bad Google, bad!

>Evolved aircraft concept requirements

>I have a bit evolved set of requirements for an aircraft concept to present. They are now as follows:

– safe
* 2 engines
* 2 fuel systems
* 2 propellers
* non-stallable
* non-spinnable
* double avionics
* two batteries
* two electrical systems
* moderate stall speed (<=55 kts)
* good brakes
* good tires and landing gear that does not break from few bounces
– economical
* very low fuel consumption
* must run on autogas or diesel oil
– at least 2 places with side by side seating, in comfort (enough space in cockpit, a lot more than in a Cessna)
– very long endurance
– capable to high altitude flight
– best glide ratio speed as high as feasible (enabling cruising at L/D max).
– very high best L/D ratio (>=1:25)
– low minimum sink rate
– relatively low power required to keep in level flight
– low drag utilizing extensive laminar flow in the fuselage and wings
– lightning strike protection (copper mesh installed to the whole aircraft)
– utility category (+4.4/-2.2G)
– positively stable in all flight conditions (suitable for IFR flight)
– speed brakes / spoilers
– ballistic recovery chute
– strong roll cage around the cockpit, exceeding the current FAR23 requirement at least with factor of two
– keeping aircraft CG on correct place do not require using ballast (no matter if there are two or one person sitting on front seats)
– aircraft can be parked without anyone sitting on it on its normal upright position
– aircraft shall look stylish and out-of-this-worldish
– surface finish has to be smooth
– large enough control panel for fitting IFR instruments (Large EFIS screen + analog backup instruments)
– good visibility outside
– rudder trim
– aileron trim
– elevator trim
– using aircraft systems has to be simple and all procedures has to be very simple and easy to memorize (aircraft shall not be a checklist-machine)

Summary: Different-looking composite aircraft that incorporates extensive laminar flow, does not stall or spin and that you can fly from Europe to Oskosh and back with ease and with peace of mind. Complies or exceeds with FAR23.

Evolved aircraft concept requirements

I have a bit evolved set of requirements for an aircraft concept to present. They are now as follows:

– safe
* 2 engines
* 2 fuel systems
* 2 propellers
* non-stallable
* non-spinnable
* double avionics
* two batteries
* two electrical systems
* moderate stall speed (<=55 kts)
* good brakes
* good tires and landing gear that does not break from few bounces
– economical
* very low fuel consumption
* must run on autogas or diesel oil
– at least 2 places with side by side seating, in comfort (enough space in cockpit, a lot more than in a Cessna)
– very long endurance
– capable to high altitude flight
– best glide ratio speed as high as feasible (enabling cruising at L/D max).
– very high best L/D ratio (>=1:25)
– low minimum sink rate
– relatively low power required to keep in level flight
– low drag utilizing extensive laminar flow in the fuselage and wings
– lightning strike protection (copper mesh installed to the whole aircraft)
– utility category (+4.4/-2.2G)
– positively stable in all flight conditions (suitable for IFR flight)
– speed brakes / spoilers
– ballistic recovery chute
– strong roll cage around the cockpit, exceeding the current FAR23 requirement at least with factor of two
– keeping aircraft CG on correct place do not require using ballast (no matter if there are two or one person sitting on front seats)
– aircraft can be parked without anyone sitting on it on its normal upright position
– aircraft shall look stylish and out-of-this-worldish
– surface finish has to be smooth
– large enough control panel for fitting IFR instruments (Large EFIS screen + analog backup instruments)
– good visibility outside
– rudder trim
– aileron trim
– elevator trim
– using aircraft systems has to be simple and all procedures has to be very simple and easy to memorize (aircraft shall not be a checklist-machine)

Summary: Different-looking composite aircraft that incorporates extensive laminar flow, does not stall or spin and that you can fly from Europe to Oskosh and back with ease and with peace of mind. Complies or exceeds with FAR23.